Optical microscopes are generally used as means for examining living biological cells, such as a cultured cell specimens cultured in a culture medium on a petri dish or a microplate. Recently, optical microscopes include highly sensitive image-acquisition parts, such as cooled CCD cameras, so as to detect weak fluorescence from a fluorescently-labeled cultured cell and record it as image data. Since the fluorescence from a fluorescently-labeled cultured cell is extremely weak, it is necessary to prevent, as much as possible, light other than fluorescence from the cell, i.e., ambient light, from being detected in order to accurately detect the weak fluorescence. Therefore, some of the commercially available optical microscope apparatuses have a structure in which an entire inverted microscope is covered with a housing in order to prevent external light from being detected or to prevent external light from being detected at least when an image is being acquired. For instance, an inverted microscope produced by General Electric Healthcare is an example of such an optical microscope apparatus.
This kind of optical microscope apparatus includes a housing that covers the entire inverted microscope and a computer-controllable motorized stage that can hold a microplate and that is movable in the XY directions. A door is formed in a section of the housing. The motorized stage holding a microplate moves outward through this door until it reaches a predetermined position. The operator can change or set a microplate while the motorized stage is at the predetermined position. The door opens when the motorized stage moves outward to the predetermined position in response to the operator's instruction and is closed when the motorized stage is stored inside the housing. In this way, light can be blocked from entering the entire inverted microscope, and additionally, the specimen environment can be maintained by using a life support device, such as a temperature regulator.
Safety mechanisms of the door sections of upright microscopes that have their image-forming optical system, observation optical system, and motorized stage stored in a housing are well known (for example, refer to Patent Document 1). According to Patent Document 1, detection part is provided for detecting the presence of a foreign object when a support base supporting the subject to be examined is drawn into the housing.
Patent Document 1:
Japanese Unexamined Patent Application, Publication No. 2003-5079